More perspective on the limits to renewables penetration

In evaluating solutions to the limits of renewables penetration, it is important to distinguish what is real from what is research. On the real side, current Wind and Solar electricity generation are mature technologies with annual investment exceeding $250B. This represents about half the world investment in new generation. Beyond investment in generation, there is also some investment in transmission to get the electricity from the remote locations where much of it is generated to where it is needed. As with all such large scale endeavors money is only invested in proven technology, low risk projects. The technologies vying for entry to the “real” proven low risk category are offshore wind and to a lesser extent Concentrated Solar Power. Its also important to understand that current wind and solar deployment rely almost completely on fossil fuel backup generation.

Technologies that are in development and not being deployed include the following:

1. most energy storage (except for pumped hydro),
2. generation of hydrogen from electrolysis
3. redundant long distance transmission within the current grid to enable transfer of intermittent power across regions,
4. control systems that monitor and control the long distance distribution of intermittent energy across large regions

Up until recently, as Wind and Solar have grown, the existing grid could adapt to their relatively small contribution. In a few markets limits are now appearing and additional infrastructure has to be contemplated. This NREL study is an attempt to forecast how the combined grids of the US east coast could achieve 30% renewables penetration by 2026. This article is a review of the report. The report is based on sophisticated modelling on a supercomputer of projected grid changes. These include growth in wind and solar in specific locations, growth in transmission and a monitoring and control system that manages balancing variable supply with variable demand. The study highlights the complexity of what seems a modest goal with limited technological changes. Fossil fuels and nuclear are still the dominant generation technologies. The model is limited. It is based on one year and does not cover worst case events. Implementing the monitoring and control aspect of the model would be technically difficult and politically really difficult. The goal is still only a modest 30% penetration.

So getting back to the theme of limits to renewables penetration, its clear that only as the problem is becoming real, is there some focus on how the problem can be solved.  We are in the very early stages of recognizing the problem. This NREL study and the more academic and theoretical Solutions Project highlight how a centralized monitoring and control system is an essential part of a solution. This, in many ways would seem a bigger problem than developing and deploying energy storage, in large part because there is a big political problem as well as a big technical problem.

The NREL study only contemplates 30% penetration and relies on significant new technology not yet developed. The solutions project relies on even more technology not yet developed and is a more simplistic model that does not model an actual interconnect. These studies at least are starting to outline the problem as opposed to ignoring it as has been the attitude so far.

As I have previously maintained, the problems with renewables penetration need to be accepted before alternative solutions are evaluated. At this stage all the technologies being investigated or developed are very far from significant deployment. When viewed from this perspective, StratoSolar is no farther from deployment and no more speculative than the technologies being contemplated by these investigations. StratoSolar specifically addresses the daytime intermittency, nighttime storage, long distance transmission and cost of generation that will limit the future penetration of current PV solar and wind generation. Its cost of development is low. The timeframe to deployment if proven is long before 2026.
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By Edmund Kelly